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东昆仑阿克楚克塞地区辉长岩地球化学特征、锆石U-Pb年龄及其构造意义 预览

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摘要 东昆仑地区基性-超基性岩石的研究较薄弱,缺乏对东昆仑幔源岩浆活动及岩浆演化的整体认识。对阿克楚克塞辉长岩进行了地球化学、锆石U-Pb年代学及Hf同位素研究,结果显示,该岩石形成于晚三叠世早期(219.3±1.1Ma,MSWD=0.80);岩石SiO2含量为49.03%~57.26%,Mg#值为49~57,属于钙碱性系列岩石;稀土元素配分曲线为轻稀土元素富集的右倾型,富集大离子亲石元素Rb、Ba、K,相对亏损高场强元素Nb、Ta、Ti;εH(ft)=-1.81~3.25,锆石Hf模式年龄大于锆石结晶年龄。地球化学特征显示,阿克楚克塞辉长岩岩浆源区应为受俯冲板片流体交代的岩石圈地幔。结合区域构造背景分析,阿克楚克塞辉长岩形成于印支期造山后伸展的构造环境,继承了早期板片俯冲改造的地幔源区特征。 The study of basite and ultrabasite in East Kunlun is relatively limited,which results in a lack of an overall understanding of mantle-source magmatic activities and magmatic evolution in East Kunlun.This paper presents geochemical,U-Pb chronological and Hf isotopic studies of gabbro in Akechukesai.The results indicate that the rock was formed in early Late Triassic(219.3±1.1Ma,MSWD=0.80).The rock belongs to calc-alkaline series.The content of SiO2 is 49.03%~57.26%and the values of Mg#are 49~57.The REE distribution curve shows right-dipping feature of LREE.The rock is enriched in LILE(Rb,Ba,K)and depleted in HFSE(Nb,Ta,Ti).TheεH(f t)values vary from-1.81 to 3.25 and the Hf model age of zircon is older than the crystallizational age of zir-con.Geochemical features of the rock indicate that the Akechukesai gabbro originated from partial melting of the metasomatized lithospheric mantle caused by the dehydration of the subducting slab.Combined with the analysis of regional tectonic setting,the au-thors hold that the Akechukesai gabbro was formed in an extensional regime of the Late Indosinian,inheriting the characteristics of mantle source altered by early subduction of slab.
作者 杨锡铭 孙丰月 赵拓飞 刘金龙 彭勃 YANG Ximing;SUN Fengyue;ZHAO Tuofei;LIU Jinlong;PENG Bo(College of Earth Sciences,Jilin University,Changchun 130061,Jilin,China;Shenyang Center,China Geological Survey,Shenyang 110000,Liaoning,China;Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China)
出处 《地质通报》 CSCD 北大核心 2018年第10期1842-1852,共11页 Geologcal Bulletin OF China
基金 青海省地质调查局项目《青海省柴达木周缘铜镍硫化物矿床成矿规律及找矿预测研究》(编号:2017042004ky004)。
关键词 辉长岩 锆石U-PB年龄 地球化学特征 大地构造背景 阿克楚克塞 东昆仑 gabbro zircon U-Pb age geochemical characteristics tectonic setting Akechukesai East Kunlun
作者简介 杨锡铭(1993-),男,在读硕士生,矿物学、矿床学、矿石学专业。E-mail:18243177359@163.com;通讯作者:孙丰月(1963-),男,博士,教授,从事矿床地质、成矿作用研究。E-mail:sfy@jlu.edu.cn。
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